$ Get Internet Price $

New 2026 Grand Design Momentum M-Class 399M

Toy Hauler Fifth Wheel

Stock #21173437

Mesa, AZ

Rainy day? No problem. The interior kitchen is a culinary playground, featuring a kitchen island, pull-out countertop extension, deep storage, pantry, and upscale appliances.

INVENTORY IMAGES SHOWN

1 of 76

+76

SALE PRICE: $164,995
MSRP: $181,832
Save: $16,837

Payments From: $1,103 /mo.

45ft long
18,000 lbs
Sleeps 4

3 slides
Kitchen Island

Two Entry/Exit Doors

See All Specs

Specifications

Sleeps	4	Slides	3
Length	44 ft 10 in	Ext Width	8 ft 5 in
Ext Height	13 ft 6 in	Int Height	8 ft 5 in
Interior Color	ARTISAN	Hitch Weight	3464 lbs
GVWR	22500 lbs	Dry Weight	18000 lbs
Fresh Water Capacity	140 gals	Grey Water Capacity	104 gals
Black Water Capacity	52 gals	Tire Size	17.5"
Furnace BTU	35000 btu	Fuel Capacity	60 gals
Available Beds	Queen	Refrigerator Type	12V Stainless Steel
Refrigerator Size	20 cu ft	Cooktop Burners	3
Number of Awnings	3	Axle Weight	7000 lbs
Garage Size	12 ft 6 in	LP Tank Capacity	30 lbs
Water Heater Type	On Demand	AC BTU	30000 btu
TV Info	LR 50" LED TV, Garage 32" LED TV, Patio 65" TV	Awning Info	9', 12', 14' Power w/LED Lights
Axle Count	3	Washer/Dryer Available	Yes
Number of LP Tanks	2	Shower Type	Shower w/Seat
Electrical Service	50 amp	VIN	573FM4736TBB04387

Description

"This is the manufacturer's minimum allowed advertised price, contact us today for your unbeatable personalized quote."

NEW 2026 Grand Design Momentum 399M Toy Hauler — Elevate Every Adventure

If you’ve been searching for a fifth wheel toy hauler that checks every box—power, luxury, workspace, entertainment, and real off-grid capability—the Momentum 399M was built for you. Grand Design’s flagship toy hauler welcomes thrill-seekers and full-timers alike with refined residential comforts and rugged durability that can keep up with wherever your journey leads.

Load Up, Level Up, and Live Large
The 12' 6" separate garage gives you the freedom to bring quads, dirt bikes, kayaks, e-bikes—anything that fuels your weekends. Once unloaded, transform the space into an extra suite with the optional Liftsuite system, complete with under-glow accent lights for a premium touch. And when you want to take the party outside, the side patio becomes your open-air living room—outfitted with a 65" TV, a 1.7 cu. ft. fridge, and an exterior griddle to keep everyone fed and smiling.

A True Chef's Kitchen… Indoors or Outdoors
Rainy day? No problem. The interior kitchen is a culinary playground, featuring a kitchen island, pull-out countertop extension, deep storage, pantry, and upscale appliances. Whether you’re prepping trail-day snacks or hosting friends for dinner, you’ll have the space and style to do it right.

Relaxation Worth Coming Home To
Kick back in the main living area where an L-shaped reclining sofa faces a 50" TV and ambient fireplace—the perfect setup after a long day on the trails. Need to squeeze in some work? The innovative hybrid desk/dinette with panoramic windows gives you a scenic remote-work station without sacrificing dining space.

Your Private Bedroom Retreat
At the front of the coach, unwind in the spacious master suite with a queen bed slide (optional king!), a large wardrobe with washer/dryer prep, and a dresser with TV prep. Whether you’re weekend camping or living full-time, this bedroom delivers the storage, comfort, and separation you need.

Built for All Seasons & All Terrains
Every Momentum is engineered for durability and all-weather performance with a fully enclosed/heated underbelly, 5-sided aluminum cage, and triple-insulated garage floor. Ride smoother with the MORryde CRE3000 suspension, rubber pin box, and upgraded axle hangers. Inside, enjoy upscale touches like hardwood cabinet doors, hidden hinges, solid surface countertops, color-changing LED lighting, and even a central vacuum system. Four premium packages—including the Garage Package, Weather-Tek Package, and Interior Luxury Package—ensure you don’t just arrive… you arrive in style.

Your Toys Deserve a Better Home. So Do You.
If you’ve dreamed of a toy hauler that works hard, plays harder, and pampers you at the end of every drive, the 2026 Momentum 399M is the one you’ll want to see first—and last.

Make it yours today at Little Dealer Little Prices—where your next adventure begins at a price you’ll feel great about.

INVENTORY IMAGES MAY BE SHOWN. COLORS AND SPECS MAY VARY. CALL FOR DETAILS.

Features

Standard Features

Exterior

Keyed Alike™ Ramp Door Latches
2nd Patio Awning w/ LED Lights
3rd Awning w/LED Lights (Main Slide-395MS)
Exterior Color Changing LED Accent Lighting
High-Gloss Gel Coat Exterior Sidewalls
Door Side Exterior Spray Port
Frameless Tinted Windows
Walk-On Roof
17.5" Spare Tire (Undermount)
MORryde Strut Assist Entry Step
Slam-Latch Baggage Doors
Mo Secure

Construction

101" Wide-Body Construction
5-Side Aluminum Cage Construction
Fully Enclosed Underbelly w/Heated Tanks and Storage

Running Gear

Upgraded Axle Hangers
Heavy Duty H-Rated Tires
Heavy Duty 7,000lb. Axles with ABS Drum Brakes (381MS, 395MS)
Heavy Duty 8,000lbs. Axles with ABS Drum Brakes (351MS)
17.5" H-Rated Aluminum Wheels
MORryde® CRE3000 Suspension System
Tow Assist ABS & Sway Mitigation System

Frame & Chassis

6-Point Hydraulic Leveling System
101" Wide Body Super Chassis

Interior

Interior Color Changing LED Accent Lighting
Hardwood Cabinet Doors w/Hidden Hinges
Recliner Sofa w/Adjustable Headrest or Flip Down Cupholders
Central Vacuum System w/ Tools and Dust Pan
Plywood Drawer Bottoms

Kitchen

Microwave
Residential Kitchen Faucet
Professional Grade Stainless Steel Cooktop
12v High Power MaxxAir Fan with Rain Sensor
Window Behind Range (N/A 395MS)
Kitchen Barstools w/Extended Countertops (351MS, 381MS)
Smart Sink w/removable cutting board, produce strainer and glass rinser

Electrical

Solar Prep (10 gauge wiring with universal MC4 connectors)
75 Amp Converter
12V Battery Disconnect

HVAC

12v High Power Fan (Kitchen)
35K BTU High Capacity Furnace
Stealth AC System w/ Insulated A/C Ducts
Attic Vent
High Capacity Heat Ducts

Plumbing

Exterior Spray Port (Door Side)
12V Tank Heaters
Sewer House Storage Area
Whole House Water Filtration System
All-In-One Enclosed Utility Center

Bedroom

Under Bed Storage Area
Individually Switched Reading Lights Over Bed
Bedside 110-Volt & USB Outlets
Window Above Master Bed Headboard
60" x 80" Queen Pillow Top Bed Mattress

Bathroom

Porcelain Toilet
Medicine Cabinet w/Mirrored Door
Undermount Lav Sink
One-Piece Fiberglass Shower w/Glass Door & Teak Bench Seat

Appliance

Fireplace with Electric Heater
Stainless Steel 20 cu. ft. Refrigerator
30" Over-The-Range Microwave

Electronics

Exterior Cable/SAT Plug-In
LED Smart TV in Living Area
Rockford Fosgate Stereo Ent. System w/HDMI and App Controls
Exterior Speakers
No-Crank Digital TV Antenna w/Booster
LED TV in Garage (NA 336M)
TravLFi On-Board WiFi Ready

Packages

Exterior Package

Satellite TV Prep
MORryde Strut Assist Entry Step
Aluminum Quad Entry Steps - Garage Entry
7,000 lb. Axles w/Self Adjusting Brakes, Wet Bolts and Bronze Bushings
17” Aluminum Wheels (120PSI Rated)
Cooper Tires® 17.5" All-Steel H-Rated Tires
Slam-Latch Baggage Doors
Frameless Tinted Windows
Exterior Security Lights
Power Patio Awning w/LED Lighting
Folding Roof Ladder
White Gel Coat Fiberglass Front Cap
12V Battery Disconnect
All-In-One Exterior Utility Center
50 Amp Service
Converter
Enclosed Fuel Station w/ Dual Fuel Tank (Single Tank 336M)
Partial Paint Gel Coat Fiberglass Front Cap

Interior Package

49" Class LED TV in Living Area
Stereo Entertainment System w/Bluetooth and App Based Controls in Living Area
Washer/Dryer Prep
On Demand Water Heater
Roller Shade Window Coverings (Main Living Area and Bedroom)
Recessed LED Puck Lighting
Solid Surface Countertops w/ Sink Covers
Stainless Steel Undermount Kitchen Sink
Chef Inspired Range & Oven w/ Cover
Kitchen Pantry w/ LED Light Strip
Garage Control Panel

Garage Package

32" Class LED TV in Garage
Protective Diamond Plate on Garage Sidewalls
2,500 lb. Rated Flush-Mount Tie-Downs
Ram-Air Garage Vents Both Sides
Tuff-Ply Gas and Oil Resistant Garage Flooring
FastRamp Rear Ramp Door
Triple Insulated Garage Floor

Weather-Tek Package

R-Value Equivalent (R-40 Roof / R-45 Floor / R-11 Sidewalls / R-40 Garage Floor / R-24 Slideroom Floor)
Fully Enclosed and Heated, Underbelly and Storage Area
Enclosed and Heated Low Point Drains
Engineered Underbelly Airflow Heat Paths
Stealth AC System w/ Insulated A/C Ducts
Attic Vent
Plumbing Line Insulation Barrier

See us for a complete list of features and available options!

All standard features and specifications are subject to change.

All warranty info is typically reserved for new units and is subject to specific terms and conditions. See us for more details.

Due to the current environment, our features and options are subject to change due to material availability.

Favorite RVs

Save your favorite RVs as you browse. Begin with this one!

Friendly service
Knowledgeable efficient friendly. Sales finance and service all great

Robert from Picacho, AZ
Excellent Service and Selection
The selection of pop up campers was the best in Arizona. Patti, my sales rep, was friendly, knowledgeable, and very responsive to all of my questions, regardless of the time or day of the week.

Benjamin from Chandler, AZ
Jan Everybody’s Favorite
Jan was wonderful to work with! She knew what we were looking for and let us know when something became available!

Karen from Mesa, AZ

We are here to help, call us at
888-834-9581 or Contact Us

We are here to help!

888-834-9581
Contact Us
$ Get Internet Price $

Please contact us @ 928-350-2400 for availability as our inventory changes rapidly. Little Dealer Little Prices strives for accurate website information but is not responsible for misprints, typos, or errors on our website. Manufacturer or sample photos and specifications may be used in place of actual unit photos and specs. Monthly payments are an estimate only and do not constitute a commitment that financing or a specific interest rate or term is available. Prices exclude taxes, PDI, documentation and delivery fees, destination charges and fees. This offer expires when this information changes or the stock number is sold.

Manufacturer and/or stock photographs may be used and may not be representative of the particular unit being viewed. Where an image has a stock image indicator, please confirm specific unit details with your dealer representative.

New 2026 Grand Design Momentum M-Class 399M

399M Floorplan

Specifications

Description

Features

Why Do We Ask You For This Information?